Project Summary The U.S. National HIV/AIDS Strategy 2020 calls for increasing access to care and improving outcomes of people living with HIV and targeting biomedical prevention efforts (including access to pre-exposure prophylaxis [PrEP]) where HIV is most heavily concentrated. Baltimore, MD; Washington, DC; and Philadelphia, PA (BWP) are disproportionately burdened by high rates of new cases of HIV infection, with disproportionate rates in young Black men who have sex with men (YBMSM) aged 15 to 24. High incidence underscores the need for increased identification, linkage and initiation in HIV and preventive care for YBMSM. Grants focused on high rates directly address NIH research priorities to reduce health disparities in the incidence of HI, in ART outcomes or in high HIV prevalent or high-risk areas. This innovative proposal seeks to test, treat and retain YBMSM living in BWP along the prevention and treatment continuums using the following aims: Aim 1. Identify and recruit young (ages 15-24) black men who have sex with men (YBMSM) in 3 urban cities who are (1) HIV-infected, not virally suppressed; and (2) high-risk HIV uninfected YBMSM, including gender variant and questioning men, using respondent driven sampling with targeted seed identification; Aim 2. Compare the efficacy of two study arms (mobile-enhanced engagement intervention (MEI) vs. standard of care (SOC)) to achieve sustained retention (measured by ? 4 follow up visits per 18 months) and engagement in HIV care (measured by durable viral suppression (HIV VL < 200 copies/ml) and substance treatment among 300 HIV infected YBMSM who are not virally suppressed and recruited from RDS; and Aim 3. Modify and implement mobile-enhanced intervention for 300 high-risk HIV uninfected YBMSM, recruited from RDS to promote linkage, retention and engagement of pre-exposure prophylaxis (PrEP) and substance treatment uptake over 12 months, comparing younger (15-19) and older (20-24) participants. The mobile-enhanced engagement intervention is driven by the expressed and self-determined needs of each HIV infected and uninfected participant and includes care navigation, engagement, treatment and adherence, with a supplemental SBIRT+ intervention, to support YBMSM who face barriers accessing substance use treatment. By building upon existing case management services and flexibility to be adapted across ages and maturity and for prevention services, this intervention has the ability to transform networks, HIV and prevention care in YBMSM in cities with very high primary and secondary HIV transmission.